The absorption, distribution, metabolism and excretion of 14C labeled allyl isothiocyanate (AITC) was studied in male and female F344 rats. AITC is readily absorbed, metabolized and excreted in the form of several metabolites. Approximately 60-70 percent of the dose is excreted in urine within 24 hr in both male and female rats following either oral or iv administration of AITC. Only 2-3 percent of the dose is excreted in feces. The whole body half-life for AITC was less than 24 hr in both sexes. High concentration of AITC derived radioactivity was present in blood and lung 15 min after administration and in liver, muscle, skin and adipose tissue 45 min after administration. Very small amounts of AITC were present 24 hr after administration. This compound appears to have little or no potential for bioaccumulation in any tissue assayed.